## **Core Concept**
The "double bubble" sign is a radiological feature observed in imaging studies, particularly in abdominal X-rays or CT scans. It is associated with a specific condition that causes obstruction and dilatation of parts of the gastrointestinal tract. This sign is crucial for diagnosing certain acute abdominal conditions.

## **Why the Correct Answer is Right**
The correct answer, **C. Duodenal atresia**, is right because the "double bubble" sign is classically associated with this condition. Duodenal atresia is a congenital obstruction of the duodenum, which prevents normal intestinal flow. This obstruction leads to the dilatation of the stomach and the proximal duodenum, creating the appearance of two air-filled structures (or "bubbles") on an abdominal X-ray. This sign is a hallmark for the diagnosis of duodenal atresia, especially in neonates.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although intestinal obstruction can cause various radiological signs, the "double bubble" sign is specifically associated with duodenal atresia, not just any intestinal obstruction.
- **Option B:** This option is incorrect as it does not specifically relate to the "double bubble" sign.
- **Option D:** This option is incorrect because the "double bubble" sign is not typically associated with this condition.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that the "double bubble" sign is highly suggestive of duodenal atresia in a neonate with bilious vomiting. This condition requires prompt surgical intervention. Remember, the presence of bile in the vomit indicates an obstruction beyond the ampulla of Vater, pointing towards a possible duodenal or more distal intestinal obstruction.

## **Correct Answer:** **C. Duodenal atresia**